In robotic packaging operations, a producer might desire to ship work products in shipping containers of a standard shape and size. The shape and size of the individual work products might be different from one job to the next. In order to ship in standard size containers it may be required to retrieve and collect the products of one size and shape on the end effector of the robot in a different pattern than for other products.
For example, in the bakery industry a producer typically will produce several sizes of loaves of bread from time to time and has one basket size in which he/she ships the products. The different products may fit best in the basket when configured in different arrangements or pack patterns than other sized products. The pack patterns are dependent of the product sizes. A robot may be used to pick the products up with multiple picks of the end effector at various positions to form the desired pattern of the products on the end effector, and the robot then places the products into the basket all at once in the desired pattern.
Usually a single vacuum source with high flow and low vacuum level for the pick-up force is desirable and most commonly used. Multiple suction cups typically are used as the vacuum retrievers to provide the seal between the vacuum source and the objects being picked. When multiple picks are required for one delivery of the products to the basket, the vacuum must be applied to certain suction cups on the end effector to enable picking or holding of the product in that pick zone while other zones of the suction surface must not allow vacuum flow because those zones of the end effector are not yet covered by work products. To accomplish this, the vacuum source may be split in several tubes and then the tubes are valved open or closed to allow vacuum to flow to different sectioned-off portions of the suction surface of the end effector.
The system described above is not ideal when several different zones are required to conduct the picking functions and/or the zones must change in shape for picking different products. If there are too many pick zones of vacuum retrievers then the vacuum lines become small and restrict the vacuum flow.
A common solution was to provide multiple end effectors that have 2 to 6 pick zones in the suction surface strategically placed for the specific pattern or similar patterns that it is designed for. This is cost prohibitive as some producers have dozens of different shaped and sized products and would require dozens of different end effectors.
Similarly, another method of having a non-zoned end effector was to have the vacuum source connected with a large hose to a large plenum. The bottom of the plenum is then populated with multiple suction cups that allow high flow between the cup and the plenum. This may be a solution to some of the problems but is limited because it is not zoned and therefore cannot perform multiple picks. If multiple picks are attempted then the first pick often fails due to leakage from the other open cups.
Therefore, there exists a need for an improved universal end effector that can be programmed to open vacuum flow to only selected zones of suction cups as required to form desired patterns or zones of suction. The end effector would minimize vacuum loss through suction cups that are not sealed over a product. Preferably, the end effector would have high enough resolution of suction cups to be able to form substantially any pattern for any common sized product to be picked and placed by a robot. The end effector would allow a high volume of vacuum flow to each suction cup that is to engage the work product substantially without loss of sub-atmospheric pressure in the vacuum source through the other suction cups, and without complex and restrictive chambers and multiple hoses.